Abstract : J.3
Detailed structure of moist, sheared, statically stable, orographic flows

Socorro Medina, Robert Houze, Nicole Asencio
University of Washington

When a mid-latitude cyclone approaches a mountain range, the airflow at low-levels is modified by the orography. This study uses detailed, high-resolution Doppler radar observations and numerical modeling to analyze moist flows upstream of the Alps for a case of statically stable strongly sheared flow in the Lago Maggiore region, on the Mediterranean side of the Alps. A synoptic-scale south-southwesterly upper-level flow was located above ~2 km, a barrier-scale east-southeasterly mid-level flow between ~1-2 km and a smaller-scale north-northwesterly low-level flow below 1 km. The heights of the transitions between these flows are underestimated by a mesoscale simulation, which then has less blocking and more upslope flow than in the real case. Within the layers of strong shear separating the three flows, turbulence occurs and has the structure of Kelvin-Helmholtz waves.